Most Common Parasitic Infections

by | Jun 12, 2019 |

A parasite is an organism that depends and lives in/on the other organisms called the host. Without a host, the parasite is not able to live. Parasites may be microorganisms (eg, malarial parasite) or may not be (worm parasites). Worldwide, millions of people get affected or die due to parasitic infections annually.

Most Common Parasitic Infections

The most common parasitic infections are described below:


  • Malaria is a mosquito-borne infection caused by a protozoan parasite of Plasmodium genus. It can be life-threatening if left untreated and is a non-communicable disease.
  • Most common symptoms of this parasitic infection include chills, headache, vomiting, fever, and sweats. In complicated cases, impaired consciousness, multiple convulsions, respiratory distress, deep breathing, jaundice, and vital organ dysfunction may occur.
  • It is diagnosed by immunologic test, microscopic examination of blood, and polymerase chain reaction.
  • Drugs used for the treatment of malaria are chloroquine, atovaquone-proguanil, mefloquine, quinine etc. These drugs should be taken only on the prescription of a doctor.


  • This parasitic infection is caused by a protozoan E.histolytica. It is a communicable parasitic infection and is transmitted by consuming contaminated food or drinks and contact with other contaminated things.
  • The symptoms of this parasitic infection include abdominal cramping, loose stool, and stomach pain. A severe form of infection causes bloody stools and fever.
  • It is mostly diagnosed by a stool test. Some routine blood tests are recommended if the infection spreads to other organs.
  • It is generally treated with metronidazole.

Leishmaniasis (kala-azar)

  • It is caused by a protozoan species of leishmania and is transmitted by some sandflies.
  • Symptoms of this parasitic infection include low blood count, fever (usually intermittent), weight loss, and increased level of immunoglobulins.
  • It is mostly diagnosed by microscopic examination of tissue and blood test for detecting antibodies
  • Treatment options for this parasitic infection include oral miltefosine and liposomal amphotericin B


  • Giardiasis is also the most common parasitic infection and caused by Giardia lamblia. It is a communicable parasitic infection and transmitted by consuming contaminated food or drinks.
  • Symptoms of giardiasis include gas, diarrhea, foul-smelling or fatty stools (they may float), and abdominal or stomach cramping.
  • It is diagnosed by stool antigen testing, an examination of duodenum fluid, and small intestine biopsy.
  • In many cases, treatment is not required, but when symptoms persist for a long duration, drugs nitazoxanide, metronidazole, and tinidazole are used.


  • Trichomoniasis is caused by organism Trichomonas vaginalis. It is a very common parasitic infection and also known as trich. It is a sexually transmitted infection and treated very easily.
  • Symptoms of this parasitic disease in women include vaginal discharge, spotting, genital itching or burning, genital swelling or redness, frequent urge for urination, pain during sexual intercourse or urination. Symptoms in men include discharge from the urethra, burning after ejaculation or during urination and frequent urge for urination.
  • It is diagnosed by cell cultures, antigen tests, and microscopic examination of vaginal fluid or urethral discharge.
  • Treatment options include tinidazole or metronidazole.


  • Ascariasis is the parasitic infection of the small intestine and is caused by Ascaris lumbricoides. It is a communicable parasitic infection and is transmitted by consuming contaminated food, water, and contact with contaminated things.
  • Symptoms include gagging or coughing, shortness of breath or wheezing, blood in the mucus, chest discomfort, fever, nausea, vomiting, diarrhea, intestinal blockage, loss of appetite, visible worms in stool, abdominal pain or discomfort, and weight loss.
  • It is generally diagnosed by a stool test. After diagnosis, the further test may be recommended including X-ray, CT-scan, MRI, ultrasound, or endoscopy
  • Treatment options include albendazole, ivermectin, and mebendazole.

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